bims-tubesc 2021-09-12 papers

bims-tubesc

Biomed News

on Molecular mechanisms in tuberous sclerosis

Issue of 2021–09–12
nine papers selected by

Renal cystic disease in tuberous sclerosis complex.
An Israeli tuberous sclerosis cohort: the efficacy of different anti-epileptic strategies.
Microglial ASD-related genes are involved in oligodendrocyte differentiation.
Rag GTPases suppress PRL-3 degradation and predict poor clinical diagnosis of cancer patients with low PRL-3 mRNA expression.
Estradiol ameliorates metformin-inhibited Sertoli cell proliferation via AMPK/TSC2/mTOR signaling pathway.
A novel role of snail in regulating tuberin/AMPK pathways to promote renal fibrosis in the new mouse model of type II diabetes.
Fission yeast TOR complex 1 phosphorylates Psk1 through evolutionarily conserved interaction mediated by the TOS motif.
[Identification of a novel TSC2 gene variant in a patient with tuberous sclerosis complex].
FMR1 and AKT/mTOR Signaling in Human Granulosa Cells: Functional Interaction and Impact on Ovarian Response.

Exp Biol Med (Maywood). 2021 Sep 06. 15353702211038378

Renal cystic disease in tuberous sclerosis complex.

Prashant Kumar, Fahad Zadjali, Ying Yao, John J Bissler.

  Tuberous sclerosis complex (TSC) is associated with TSC1 or TSC2 gene mutations resulting in hyperactivation of the mTORC1 pathway. This mTORC1 activation is associated with abnormal tissue development and proliferation such that in the kidney there are both solid tumors and cystic lesions. This review summarizes recent advances in tuberous sclerosis complex nephrology and focuses on the genetics and cell biology of tuberous sclerosis complex renal disease, highlighting a role of extracellular vesicles and the innate immune system in disease pathogenesis.

Keywords:  Tuberous sclerosis complex; cell nonautonomous trait; extracellular vesicles; renal cysts

DOI:  https://doi.org/10.1177/15353702211038378
Childs Nerv Syst. 2021 Sep 07.

An Israeli tuberous sclerosis cohort: the efficacy of different anti-epileptic strategies.

Omer Shlomovitz, Bruria Ben-Zeev, Oren Pleniceanu, Shoshana Greenberger, Einat Lahav, Sharon Mini, Michal Tzadok.

   AIM: We aimed to describe the experience of a large single-center cohort for the clinical, radiological, and genetic characteristics, as well as to determine the efficacy of different anti-epileptic strategies in children and adults with tuberous sclerosis complex (TSC).
METHODS: We carried out a historical cohort study on 91 TSC patients treated in a single center between 2008 and 2018.
RESULTS: Our cohort comprised 46 males and 45 females, with a median age of 15.6 years at the last follow-up. Mean follow-up time was 2.5 ± 0.75-5.5 years (range 0-9.5 years). Of those tested, a disease-causing mutation was identified in 90% of patients, 53% in TSC2, and 37% in TSC1. Epilepsy prevalence was similar among TSC1 and TSC2 mutated patients. The most common radiological finding were cortical tubers in 95% of patients, while subependymal giant cell astrocytoma (SEGA) were detected in 36% of patients. Notably, infantile spasms (IS) were diagnosed in 29%, with SEGA representing the only finding significantly different in prevalence between those with and without IS (62% vs. 28%, respectively, p = 0.009). Lastly, we did not find any difference in efficacy between three anti-epileptic treatments: Vagus nerve stimulation (VNS), CBD-based products, and the ketogenic diet, all showing approximately 30%-40% response rates.
SIGNIFICANCE: Altogether, we provide a comprehensive description of our experience in treating TSC, which could serve to expand current knowledge of the disease and its treatments.

Keywords:  CBD; Infantile spasms; Ketogenic diet; TSC; Vagus nerve stimulation

DOI:  https://doi.org/10.1007/s00381-021-05348-9
Sci Rep. 2021 Sep 08. 11(1): 17825

Microglial ASD-related genes are involved in oligodendrocyte differentiation.

Yuta Takanezawa, Shogo Tanabe, Daiki Kato, Rie Ozeki, Masayo Komoda, Tatsunori Suzuki, Hiroko Baba, Rieko Muramatsu.

Autism spectrum disorders (ASD) are associated with mutations of chromodomain-helicase DNA-binding protein 8 (Chd8) and tuberous sclerosis complex 2 (Tsc2). Although these ASD-related genes are detected in glial cells such as microglia, the effect of Chd8 or Tsc2 deficiency on microglial functions and microglia-mediated brain development remains unclear. In this study, we investigated the role of microglial Chd8 and Tsc2 in cytokine expression, phagocytosis activity, and neuro/gliogenesis from neural stem cells (NSCs) in vitro. Chd8 or Tsc2 knockdown in microglia reduced insulin-like growth factor-1(Igf1) expression under lipopolysaccharide (LPS) stimulation. In addition, phagocytosis activity was inhibited by Tsc2 deficiency, microglia-mediated oligodendrocyte development was inhibited, in particular, the differentiation of oligodendrocyte precursor cells to oligodendrocytes was prevented by Chd8 or Tsc2 deficiency. These results suggest that ASD-related gene expression in microglia is involved in oligodendrocyte differentiation, which may contribute to the white matter pathology relating to ASD.

DOI: https://doi.org/10.1038/s41598-021-97257-9
Biochem Biophys Res Commun. 2021 Aug 31. pii: S0006-291X(21)01272-9. [Epub ahead of print]576 108-116

Rag GTPases suppress PRL-3 degradation and predict poor clinical diagnosis of cancer patients with low PRL-3 mRNA expression.

Yin Shi, Shengfeng Xu, Natalie Y L Ngoi, Yuanjian Hui, Zu Ye.

  Ras-related GTP binding (Rag) GTPases are required to activate mechanistic target of rapamycin complex 1 (mTORC1), which plays a central role in cell growth and metabolism and is considered as one of the most important oncogenic pathways. Therefore, Rag GTPases have been speculated to play a pro-cancer role via mTOR induction. However, aside from stimulation of mTOR signaling, firm links connecting Rag GTPase activity and their downstream effectors with cancer progression, remain largely unreported. In this study, we reported a novel link between RagB/C and a known oncoprotein phosphatase of regenerating liver-3 (PRL-3) by screening 22 pairs of tumors and their adjacent normal tissues from gastric, liver and lung cancers, and validating our findings in cancer cell lines with ectopic RagB/C expression. RagB/C was found to enhance PRL-3 stability by modulating two major cellular protein degradation pathways: lysosomal-autophagy and ubiquitin-proteasome system (UPS). Functionally, we identified the correlation between RagB/C expression with poor clinical outcomes in breast or colon cancer patients who also showed low PRL-3 mRNA expression from data retrieved from TCGA datasets, highlighting the potential relevance of Rag GTPase and PRL-3 mRNA in combination as a prognostic clinical biomarker.

Keywords:  PRL-3; Protein stability; Rag GTPases

DOI:  https://doi.org/10.1016/j.bbrc.2021.08.090
Theriogenology. 2021 Aug 28. pii: S0093-691X(21)00307-1. [Epub ahead of print]175 7-22

Estradiol ameliorates metformin-inhibited Sertoli cell proliferation via AMPK/TSC2/mTOR signaling pathway.

Jiao Jiao Zhang, Ya Qi Li, Yu Sha Wang, Liang Chen, Xian Zhong Wang.

  Metformin is a commonly used for treating type 2 diabetes and it acts on a variety of organs including the male reproductive system. 17β-estradiol plays an important role in Sertoli cell (SC) proliferation which determines the germ cell development and spermatogenesis. The aim of this study is to investigate the effect of metformin on immature chicken SC proliferation and the potential mechanisms by which 17β-estradiol regulate this process. Results showed that metformin significantly inhibited SC proliferation, whereas 17β-estradiol weakened the inhibitory effects of metformin on SC viability, cell growth, and cell cycle progression. SC proliferation-inhibiting effect of metformin exposure was regulated by decreasing adenosine triphosphate level and respiratory enzyme activity in the mitochondria; this process was possibly mediated by the adenosine monophosphate-activated protein kinase (AMPK)/tuberous sclerosis complex 2 (TSC2)/mammalian target of rapamycin (mTOR) signaling pathway, which was regulated by the down-expressed miR-1764 and by the decreased antioxidant enzyme activity and excessive reactive oxygen species generation. In addition, SCs transfected with the miR-1764 agomir led to an improvement of proliferation capacity through down-regulating AMPKα2 level, which further decreased TSC2 expression and induced mTOR activation. However, the anti-proliferative effect of miR-1764 antagomir can be alleviated by 17β-estradiol treatment via the up-expression of miR-1764 in transfected SCs. Our findings suggest appropriate dose of exogenous 17β-estradiol treatment can ameliorate the inhibitory effect of metformin on SC proliferation via the regulation of AMPK/TSC2/mTOR signaling pathway, this might reduce the risk of poor male fertility caused by the abuse of anti-diabetic agents.

Keywords:  AMPK; Estradiol; Metformin; Sertoli cell; TSC2; mTOR

DOI:  https://doi.org/10.1016/j.theriogenology.2021.08.030
FASEB Bioadv. 2021 Sep;3(9): 730-743

A novel role of snail in regulating tuberin/AMPK pathways to promote renal fibrosis in the new mouse model of type II diabetes.

Sitai Liang, Mukesh Yadav, Kristine S Vogel, Samy L Habib.

  Epithelial-mesenchymal transition (EMT) plays an important role in tissue fibrosis following chronic exposure to hyperglycemia. This study investigates the role of chronic diabetes in regulating tuberin/snail/AMPK to enhance EMT and increase renal fibrosis. A new mouse model of db/db/TSC2 +/- was generated by backcrossing db/db mice and TSC2 +/- mice. Wild type (WT), db/db, TSC2 +/- and dbdb/TSC2 +/- mice were sacrificed at ages 6 and 8 months old. Tuberin protein level was significantly decreased in kidneys from diabetic compared to WT mice at both ages. In addition, tuberin and E-cadherin protein levels were significantly decreased in dbdb/TSC2 +/- compared to TSC2 +/- and db/db mice. In contrast, p-PS6K, NFkB, snail, vimentin, fibronectin, and α-SMA protein levels were significantly increased in dbdb/TSC2 +/- compared to db/db and TSC2 +/- mice at ages 6 and 8 months. Both downregulation of AMPK by DN-AMPK and downregulation of tuberin by siRNA resulted in increased NFkB, snail, and fibronectin protein expression and decreased E-cadherin protein expression in mouse primary renal proximal tubular cells. Interestingly, downregulation of snail by siRNA increased tuberin expression via feedback through activation of AMPK and reversed the expression of epithelial proteins such as E-cadherin as well as mesenchymal proteins such as fibronectin, NF-KB, vimentin, and α-SMA in mouse primary renal proximal tubular cells isolated from kidneys of four mice genotypes. The data show that chronic diabetes significantly decreases tuberin expression and that provides strong evidence that tuberin is a major key protein involved in regulating EMT. These data also demonstrated a novel role for snail in regulating of AMPK/tuberin to enhance EMT and renal cell fibrosis in diabetes.

Keywords:  AMPK; EMT; NFkb; diabetes; fibronectin; snail; tuberin

DOI:  https://doi.org/10.1096/fba.2020-00134
J Cell Sci. 2021 Sep 09. pii: jcs.258865. [Epub ahead of print]

Fission yeast TOR complex 1 phosphorylates Psk1 through evolutionarily conserved interaction mediated by the TOS motif.

Yuichi Morozumi, Ai Hishinuma, Suguru Furusawa, Fajar Sofyantoro, Hisashi Tatebe, Kazuhiro Shiozaki.

  TOR complex 1 (TORC1) is a multi-subunit protein kinase complex that controls cellular growth in response to environmental cues. The regulatory subunits of mammalian TORC1 (mTORC1) include RAPTOR, which recruits mTORC1 substrates, such as S6K1 and 4EBP1, by interacting with their TOR signaling (TOS) motif. Despite the evolutionary conservation of TORC1, no TOS motif has been described in lower eukaryotes. Here, we show that the fission yeast S6 kinase Psk1 contains a TOS motif that interacts with Mip1, a RAPTOR ortholog. The TOS motif in Psk1 resembles those in mammals, including the conserved Phe and Asp residues essential for the Mip1 interaction and TORC1-dependent phosphorylation of Psk1. The binding of the TOS motif to Mip1 is dependent on Mip1 Tyr-533, whose equivalent in RAPTOR is known to interact with the TOS motif in their co-crystals. Furthermore, we utilized the mip1-Y533A mutation to screen the known TORC1 substrates in fission yeast and successfully identified Atg13 as a novel TOS motif-containing substrate. These results strongly suggest that the TOS motif represents an evolutionarily conserved mechanism of the substrate recognition by TORC1.

Keywords:  Fission yeast; Mip1; TOR complex 1 (TORC1); TOS motif

DOI:  https://doi.org/10.1242/jcs.258865
Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2021 Sep 10. 38(9): 877-879

[Identification of a novel TSC2 gene variant in a patient with tuberous sclerosis complex].

Linli Liu, Chunshui Yu, Herong Yang, Qinglian Lu, Fei Ouyang, Tingting Liu.

OBJECTIVE: To explore the genetic basis for a patient diagnosed with tuberous sclerosis complex (TSC).
METHODS: Peripheral blood samples of the patient and his parents were collected for the extraction of genomic DNA. Next generation sequencing (NGS) was carried out to detect potential variant, and the result was verified by Sanger sequencing.
RESULTS: The patient was found to harbor a heterozygous c.1053delG (p.Glu352SerfsX10) frameshifting variant of the TSC2 gene. The same variant was not found in his unaffected parents and 100 unrelated healthy controls. Based on the American College of Medical Genetics and Genomics guidelines, the variant was predicted to be pathogenic (PVS1+PS2+PM2).
CONCLUSION: The novel c.1053delG (p.Glu352SerfsX10) frameshifting variant of the TSC2 gene probably underlay the TSC in this patient.

DOI: https://doi.org/10.3760/cma.j.cn511374-20200610-00429
J Clin Med. 2021 Aug 30. pii: 3892. [Epub ahead of print]10(17):

FMR1 and AKT/mTOR Signaling in Human Granulosa Cells: Functional Interaction and Impact on Ovarian Response.

Julia Rehnitz, Edison Capp, Birgitta Messmer, Xuan Phuoc Nguyen, Ariane Germeyer, Alexander Freis, Jens Erik Dietrich, Karin Hinderhofer, Thomas Strowitzki, Peter H Vogt.

  We aimed to determine whether a functional link with impact on female ovarian reserve exists between FMR1 expression and expression ratios of AKT/mTOR signaling genes in human granulosa cells in vivo, as suggested from prior in vitro data. Three hundred and nine women, who were classified as normal (NOR; n = 225) and poor (POR; n = 84) responders based on their ovarian reserve, were recruited during stimulation for assisted reproductive techniques. Expressions of FMR1 and of key genes of the AKT/mTOR and AKT/FOXO1/3 signaling pathways were comparatively analyzed in their granulosa cells. FMR1 expression in granulosa cells of NOR and POR correlated significantly with AKT1, TSC2, mTOR, and S6K expression. No correlation was found between FMR1 and FOXO1 in all, and FOXO3 expression in POR, patients. AKT1 expression was significantly higher and FOXO1 expression lower in POR samples, whereas AKT1 expression was lower and FOXO1 expression was higher in NOR samples. In human native granulosa cells, FMR1 expression significantly correlated with the expression of key genes of the AKT/mTOR signaling pathway, but not with the FOXO1/3 signaling pathway. Our data point to a functional link between FMR1 expression and expression of the AKT/mTOR signaling pathway genes controlling human follicular maturation.

Keywords:  AKT1; FMR1; FOXO1; FOXO3; S6K; TSC2; granulosa cells; mTOR; ovarian response

DOI:  https://doi.org/10.3390/jcm10173892